DESCRIPTION

The AtFS Toolkit Library extends the AtFS attribute handling. It
introduces additional standard attribute names and a list of attribute
value types.
atRetAttr returns a string representation of the value(s) of the aso
attribute named attributeName. If the attribute value is preceded by a
value special character (see list below), it will be evaluated
accordingly. When the evaluation fails, the original attribute value,
including value special character, is returned. When the attribute
value is empty, an empty string is returned. When the attribute does
not exist or on any other error condition, a null pointer is returned.
Attribute citations (like 7.0) in attribute values will always be
expanded by atRetAttr. There is no way to disable attribute expansion.
If you need the raw, unexpanded attribute value, use af_retattr (manual
page af_attrs(3)).
The attribute value returned by atRetAttr either resides in static
memory (in case of AtFS standard attributes) or in allocated memory.
Use atFreeAttr on each attribute value returned by atRetAttr when this
not needed any longer. This will recycle allocated memory if possible.
atSetAttr sets the attribute attribute for aso. It calls af_setattr
(manual page af_attrs(3)) and hence understands the modes AF_ADD,
AF_REMOVE, and AF_REPLACE. Alternatively, the mode argument is ignored,
when the equal sign between attribute name and value is preceded by
either a plus (+) or a minus (-) sign for adding and deleting attribute
values. The value special character at (@) will also be evaluated.
atSetAttr opens the file and reads its contents. If either the opening
or reading fails, the attribute setting is aborted and returns FALSE.
On successful execution, atSetAttr returns TRUE, otherwise FALSE.
atSetAttrFile evaluates a file containing attributes. If opens the
named file (filename) and interprets each line in the file as attribute
argument to atSetAttr.
atAttrName fills a static memory buffer with the name of the given
attribute and returns a pointer to this buffer. Subsequent calls of
atAttrName overwrite previous results.
atAttrValue returns a pointer to the value part of attribute.
atMatchAttr checks if aso has the given attribute. Result values are
TRUE or FALSE. If just an attribute name is given, atMatchAttr returns
a positive result if the attribute exists in the asos attribute list
or, in the case that it is a standard attribute, if it’s value is non
null. A full attribute (name and value) must match an attribute in the
asos attribute list. The value of the given attribute argument may be a
(sh(1)) pattern.

ATTRIBUTEFORMAT

Attributes have the general format name=value. Additionally, a plus or
minus sign may precede and a value special character may follow the
equal sign (<name>[+-]=[^@!*]<value>).
plus (+)
A plus sign preceding the equal sign indicates, that the value
shall be added to existing values (no matter if there are
any).
minus (-)
With the minus sign, the value shall be removed from the list
of values, if it exists.
The following is the complete list of value special characters
recognized by AtFStk.
circumflex (^)
The value is regarded as a reference to a file or ASO carrying
the real attribute value as contents.
at (@) An attribute value starting with an at (@) is considered to be
a file name from where the real attribute value is to be
taken. In contrary to the circumflex notation above, this
causes the file read only once, when setting the attribute
value.
exclam (!)
This introduces execution attributes. The attribute value is
regarded as command to be passed to a shell process. On
access, the command will be executed and its output will be
catched as real attribute value.
asterisk (*)
This denotes a pointer attribute modeling relationships
between attributed software objects. When atSetAttr finds an
attribute value with an asterisk as first character it
interprets the remaining value string as version identifier
and tries to bind it using atBindVersion (manual page
atbind(3)). On success, the network path (see
atNetworkPath(3)) of the identifies ASO will be stored as
attribute value together with the leading asterisk. atRetAttr
maps pointer attributes to local pathnames using atLocalPath
(manual page atnetwork(3)).

STANDARDATTRIBUTES

There are a number of standardattributes defined by the AtFS toolkit
library and by AtFS (Attribute Filesystem) for each ASO. For a list of
the AtFS standard attributes see the af_attrs(3) manual page. This is
a list of all standard attribute names defined in AtFStk.
Header A compound attribute consisting of a $Header: Label followed by
the bound file name (AF_ATTBOUND), the version date (vtime -
see below), the versions author and state and a trailing dollar
sign ($). Example:
$Header: attrs.c[1.1] Tue Dec 1 17:01:10 1992 andy@cs.tu-
berlin.de proposed $
Log The versions modification history from the very beginning. This
might be long.
note The modification note of the version as set by the author.
pred, succ
The physical predecessor/successor version as stored in AtFS.
If there is none, the string n/a (not available) is returned.
vtime The version date. For busy versions, this is the date of last
modification, for saved versions, it is the saving date.
xpon, xpoff
Pseudo attribute turning attribute expansion on and off (see
above).
Some other names are mapped to the appropriate AtFS standard name:
AtFStknameAtFSname(constantdefinition)AtFStknameAtFSname(constantdefinition)
atime AF_ATTATIME revision AF_ATTREV
author AF_ATTAUTHOR self AF_ATTBOUND
ctime AF_ATTCTIME selfpath AF_ATTBOUNDPATH
dsize AF_ATTDSIZE size AF_ATTSIZE
generation AF_ATTGEN stateAF_ATTSTATE
host AF_ATTHOST stime AF_ATTSTIME
lock AF_ATTLOCKER syspath AF_ATTSPATH
ltime AF_ATTLTIME type AF_ATTTYPE
mtime AF_ATTMTIME unixname AF_ATTUNIXNAME
name AF_ATTNAME version AF_ATTVERSION
owner AF_ATTOWNER
atSetAttr may also be used to set standard attributes where possible.
Attributes that may be altered are
AttributeMappedtoAtFSfunction
author af_chauthor (af_protect(3))
generation, revision, versionaf_svnum (af_version(3))
mode af_chmod (af_protect(3))
owner af_chowner (af_protect(3))
state af_sstate (af_version(3))
note af_snote (af_note(3))

RETURN VALUES

On error, the atError variable is set to a nun null value, and atErrMsg
holds a diagnostic message. atRetAttr returns a null pointer on error,
or if the desired attribute does not exist. atSetAttr and
atSetAttrFile return FALSE on any error condition. atMatchAttr returns
FALSE if an error occurred or if the attribute does not match.